Process for the production of alkali phosphates from metal phosphorus compounds



Patented Apnll, 1933 V v 1,903,532 P 'coNwAY; B'Aizonv x crns'nwrinn, grins wmnmAnN, AND "ennnanninonsnnnfor 1 .FRANKFORT-ON-THE-MAIN,(GERMANY, nssrenons'ro AMERiCAN: LUBGI GORPORA- r rion, on" NEW You; n Y.,A'CORPO(RATIONVVOF NEW YORK rnocnss r03. THE rnonuc'rron or; ALKALI rnosrnn'rns r3019! META rrrosrnonus" 'No DrawingQ Applicationflled January 21,1931,:SerialNo;'510,320, and in Germanylanu ariy 271; 1936. i

a This inventionfrelates to a process forithe prpduction of alkali Ph p from metal phosphorus compounds. 7 v v },It is known to-convert metal phosphorus compounds, especially iron; phosphide, into alkali phosphates by decomposition with alkalig sulphates, at elevated temperatures.

Thus for example it has been proposed to heat a mixture of ferro phosphorus containing 12.5% of phosphorus and corresponding to the formula Fe P, to'ared heat with sodium It has been shown that when decomposing. high percentage phosphorus alloys the quantity of metal added in conjunction with the phosphorus is not sufficient to combine with.

all the sulphur set free from the alkali sul- V phate and that in this case the sulphurescapes in the form of sulphur dioxide, for example according to the equation:

The removal of large quantities of sulphur f dioxide produced in this manner on a large scale is a matter of the greatest difiiculty, if

there is no possibility of utilizing it in situ. If for example it should be desired to dilute the Waste gases with air to such an extent that they can be allowed to escape into the atmosphere, the'quantity of air required would be so largeas to render the economy of the whole process very doubtful.

It has now been found in accordance with the present invention that it is possible to avoid this drawback by allowing the reaction between the metal phosphorus alloy and the alkalisulphate to take place inthe presence" of substances which are'adapted to convert the sulphur set free during the decomposi tion,- so far as it has not already combined with the metal added in the form of phos-' phorus alloy, into a form in which it is pref vented from being oxidized to form S0 especially in the presence of the said substances coMroUNns i 2 an amount sufficient to combine pracin tically all this sulphur. Suitable substances v to be added 'are chiefly'metal's .ofothe most diverse kinds, and also non-metallic, inorganio or organicreducing agents, such asffor example, carbonfor coal in any form, or sub-' v stances containing carbonor coal therelaction' proceeding in thepresen ce of coal; for

example, in thefollowing manner 2Fe2P-l 3Na SQ;+3G= 1 :v The presentprocess furthermore offers the advantage that it is possible completelyto combine all the sulphurcontained in the al- -kali sulphate+when employingfor example iron orcoal or the-like as the reducingaddi,

'tional substance,with the iron present in the charge in the for'm of iron sulphide: and 'to render said sulphur usefuL When employingcoal the' content of-sulphur in the iron sulphide can be increased in this mannerjto about29%, Whilst in the absence of coal a sul I l ur content up to about 23% m c n b at; tamed in the iron sulphide. ,1

applicable with particular advantage-to a 1 process for the decomposition "of metal phos- 'im etal" phosphorus alloys'with" alkali; sulphorus alloy is introduced into thefu'sed alkali sulphate,as"well as in the case of another process according to which the components 2 tons 'ofiron pliosphide containing- 2 2% I of phosphorouslare melteddowniwith fi tons I 237 .The hereindescribed; method: ofworking is phorus alloys,-.especially high percentage l 1 i 530 phates; 'according'towhich'the metal phos- 1.; 1,: A process {for resistance furnacei i No'losses of sulphuridu'ef to the formation-of sulphur dioxide occur in this fusion process. The'melt is lixiviatedjin ducing agentbeing present in an amountsuf- I ficient to protect practically V which is notsuflicient as such to combine with all the sulphur of the alkali sulphate,- the refromoxidation to S 2. A process, for the production of alkali phosphates which comprises decomposingcat elevated temperatures in the presence ofa reducing agent an alkali sulphate with ferrophosphorus, the 'iron content of which is not 7 "oxidation to S0 12 sufficient-as such to combine with allthe sulphur 'of' the alkali sulphate, the reducing agent being present in an amount sufficient to protect practically all f the sulphur from 3. A process for the production of sodium phosphate which comprises decomposing at elevated temperatures in the presence of a reducing agent sodium'sulfate with ferrophosphorus, the iron contentof which is not I suflicient as such to combine withallthe sulphur of the sodium sulphate, the reducing agent being present in an amount suflicient to protect practically all thecsulphur from oxidation to S0 7 x 4. A process forthe production alkali phosphates which comprises decomposing at elevated temperatures inthe presence of: a

carbonaceous reducing agent an alkalisfll all the sulphur with a carbonaceoussubstance ina sufficient amount to protect practically, all'thesulphur fromoxidation to S0 V 8. A process for the'production of. alkali phosphates, which comprises melting down an alkali sulphate together'with ferrophosphorus,the iron content of which is not suff cient as such -tocombine with all the sulphur of the alkali sulphate,-andftogether with coal in a sufiicient amount to protect practically all theesulphllr from Oxidation t 7 I o 9. A process forthe production'of alkali phosphates, which comprises melting down i inanelectric furnace an alkali sulphate together with ferrophosphorus, the iron 'content of which isinot s'ufiicie nt as-such'to 'combine with all the sulphur of the alkali'isulphate, and together'with carb'onin a sufs ficient amount" to protect practically all the sulphur from oxidation to S0 tures.

' 'GERHARD" ROESNER;

HANS WEIDMANN. V

ph'ate with 'a metal phosphorus alloy, the a metal content of whichis not sufficient as V such'to combine with all, the sulphurofthes alkali sulphate, the reducing agent being 7 present in an amount sufficient tote-protect practically all the sulphurcfrom oxidationto l SO process for the production, of alkali phosphates whichcomprises decomposing at elevated temperaturesin' the presenceof coal metal an alkali sulphate with a metal phos V phorusialloy, the m'e'talflcontent of which is not sufficient as such to combine with all the sulphur'ofthe alkali sulphate, the metal bean alkali sulphate with'a metal, phosphorus "alloy, the. metal content of which-is not-su-f-Y ficient as such to combinevwith all the sulphur of the alkali sulphate, the coal beingpresent in an amount sullicient to protectpractically allthesulphur from oxidation toSO p 6. Aprocess for the production of alkali I phosphates which comprises decomposing at elevated temperatures in the presence of a M V ingadded in anfamount suflicient'toprotec't v practically allthe' sulphur from oxidationto ,7.,A {process for the production of alkali V phosphates, which comprises melting down analkali sulphate together with a metal phose phorus alloy, the metal content of which is J not sufficient as, such to combine with all the i 35' sulphur of the alkali sulphate,and together v CONWAY, :BARON voh GIR SEW ALD. .i 

